Highly integrated semiconductor circuits are increasingly important, particularly in producing battery operated devices such as cell phones, portable computers such as laptops, notebook computers and PDAs, wireless email terminals, MP3 audio and video players, portable wireless web browsers and the like, and these sophisticated integrated circuits increasingly include on-board data storage, logic circuitry, and/or signal processing.
The increased density of devices in integrated circuits and the combination of various types of circuitry, such as logic and radio frequency processing circuits, have generally increased the amount of noise in various circuits. Noise can be detrimental in integrated circuits because the integrity of the signal can be compromised, which can in turn cause a loss of data or errors in logic or signal processing.
Commonly, devices in an integrated circuit are formed in a doped well to isolate substrate noise. The doped well is typically able to reduce noise between other devices in the substrate and devices in the doped well by providing a low resistance path for the noise to travel to a ground node rather than affect devices in the doped well.
In processing these integrated circuits, typically various dielectric layers are formed on the substrate and etched to form openings for metallization layers. A plasma etch process, such as a reactive ion etch (RIE), is common for etching these openings. The openings generally extend to some underlying conductive feature, and the plasma used for the plasma process is able to contact the conductive feature. In structures having devices in the doped well, charges from the plasma can be transferred through the conductive feature to the doped well.